摘要:

L'Autore ha studiato l'effetto citologico dell'arancio di acridina sui meristemi radicali di bulbi di cipolla e di semi germinati di fava. Le esperienze, con concentrazioni di arancio di acridina da 100 a 5 ppm, hanno dimostrato un'azione mutagena del colorante al buio, confermando, per tipi e frequenze di aberrazioni cromosomiche, i dati forniti da D'AMATO (1950). Le stesse concentrazioni sono state del tutto inattive come mutagene sul testViciaal buio.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796025

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

1.- Chromosome numbers in the genusBothriochloarange from 2n= 40 to 2n= 180 in multiples of 10.2.- Meiotic behavior varies from very regular in the New World species to very irregular in some of the Old World species.3.- Occurrence of aneuploidy is very rare in natural species ofBothriochloa.4.- Intergeneric and interspecific hybrids involving parents at different ploidy levels, can be obtained in the Bothriochloininae.5.- Occurrence of aneuploidy is common in some hybrids.6.- The extra chromosomes in the aneuploid plants do not differ in size or morphology from the normal chromosomes in the basic complement.7.- In the New World species ofBothriochloa, absence of aneuploidy seems to be correlated with cleistogamy and regular meiosis.8.- In the Old World species ofBothriochloa, a high degree of apomixis and some form of natural selection for complete genomes seem to be the reasons for extremely rare occurrence of aneuploid plants in nature.9.- In areas where forms ofBothriochloawith a high degree of sexuality are found natural aneuploids may be present.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796026

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

The author has studied the influence of seven carbohydrates known to occur in the ripe tomato fruit and of a mixture of two of them on growth inColletotrichum coccodes.For the investigation five monoconidial isolates from four cultures of different origin have been used. The carbohydrates were tested at indentical carbon levels in a mineral medium buffered at pH ca. 6.0 and mycelial growth was determined at intervals of 5 days after seeding.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796027

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

Nella genesi delle uova partenogenetiche inDaphnia magna, vengono prodotte delle particolari cellule somatiche, le quali si dispongono solo attorno ad uno dei quattro ovociti raggruppati, formando una sorta di « follicolo » incompleto. Questo ovocita (generalmente il terzo), attorniato dalle cellule follicolari, presenta un maggiore metabolismo, si accresce di più e diviene un uovo, mentre gli altri tre, privi di queste cellule, raggiungono un minor grado di accrescimento, sono incapaci di elaborare tuorlo e cedono il loro contenuto all'ovocita definitivo, funzionando come cellule nutrici. Pertanto si ammette che le cellule del « follicolo » esplichino un ruolo importante nel differenziamento dell'ovocita e nella successiva genesi del tuorlo inducendo in questo una elevata attività metabolica.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796028

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

Dennstaedtiaholds a pivotal position in the phylesis of leptosporangiate ferns, as evidenced from different systems of classification especially proposed by HOLTTUM (1947, 1949). There esists presently a great controversy about a possible relation betweenDennstaedtiaand Pteroids, previously held by BOWER (1926), COPELAND (1947) and HOLTTUM (l. c.). The major objection concerns the cytological discontinuity betweenDennstaedtiaand Pteroids (cf.MANTON and SLEDGE 1954; MANTON 1958; MEHRA 1961). The present report of n = 30 in JapaneseDennstaedtia hirsuta(Sw.) Mett. possibly bridges the gap, in a cytological sense, towardsPteris.Nevertheless, it is pointed out that in the phylesis of larger groups emphasis must be laid on comparative morphology.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796029

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

The author has studied the cytological effect, in onion root tips, of 6 pyrrolizidine alkaloids already known to be hepatotoxic in mammals and mutagenic inDrosophila.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796030

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

Observations are made on the meiotic behaviour and morphology of the somatic chromosomes inMicrosorium punctatum(L.) Copel, andM. membranaceum(Don.) Ching. Both species shown= 36 and 2n= 72.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796031

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

InDugesia benazziil'incrocio fra femmina del biotipo diploide e maschio del biotipo tetraploide può dare origine a nati triploidi nel corredo somatico, esaploidi in quello femminile e diploidi in quello maschile. Le caratteristiche del ciclo cromosomico di questi nati sono del tutto diverse da quelle del biotipo paterno, dal quale hanno pur ricevuto due assetti aploidi.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796032

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

The present paper deals with the cytology including karyotype analysis of eight species and varieties ofBegonia, viz.B. pauperculaKing, (2n= 22);B. rexPutz., (var. I), (2n= 22);B. rexPutz. (var. II), (2n= 32);B. rexPutz. (var. III), (2n= 34);B. malabaricaLam., 2n= 28);B. laciniataRoxb. (var. I), (2n= 20);B. laciniataRoxb. (var. II), (2n= 22);B. sp.(unidentified), (2n= 28). In addition to these two varietiesB. giganteaWall., and two varieties ofB. semperflorens, were observed. One of the former two varieties showed 2n= 28, 32 and 34 chromosomes and in another 2n= 40 and 42 chromosomes were counted in the somatic tissue and the latter in meiosis showed 40 to 46 chromosomes. The implications of such aneuploid numbers have been pointed out.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796033

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor

摘要:

L'Autore descrive lo sviluppo del gametofito femminile diSenecio leucanthemifoliusPoir. var.pinnatifidusFiori, varietà che è diffusa prevalentemente lungo le coste del Mediterraneo occidentale.

ISSN:0008-7114    

DOI:10.1080/00087114.1961.10796034

出版商:Taylor & Francis    

年代:1961

数据来源: Taylor